If $A$ and $B$ are square matrices of order $3$, $A$ is non-singular, and $AB = O$, then $B$ is a:

$A$ wire of resistance $4\,\Omega$ is stretched to twice its original length. The resistance of the stretched wire would be ................ $\Omega$.

The area (in square units) of the circle which touches the lines $4x + 3y = 15$ and $4x + 3y = 5$ is

What is the genetic material of the Tobacco Mosaic Virus $(TMV)$?

Dry distillation of calcium acetate and calcium formate forms:

$A$ particle of mass $4 M$ which is initially at rest explodes into three pieces of masses $M$,$M$ and $2 M$. The equal masses move along $X$ and $Y$-axes with velocities $4 ~ms^{-1}$ and $6 ~ms^{-1}$,respectively. The magnitude of the velocity of the heavier mass is